Sweet Potato Sourdough Burger Buns
These buns are super soft and fluffy get hold up to a fish burger nicely. The sweet potato gives it a bit of extra sweetness while the tangzhong helps with flavour and freshness. They are topped with black, white and golden sesame seeds.
Substitute mashed sweet potato for the mashed potatoes above to make these.
For 8 buns about 65 g each
egg wash: 1 yolk, 1 tbsp milk and a pinch of salt, beaten…
Mix the levain ingredients in a jar or pyrex container with space for at least 300% growth.
Press down with your knuckles or silicone spatula to create a uniform surface and to push out air.
At a temperature of 76ºF, it typically takes up to 10-12 hours for this stiff sweet levain to be at peak. For my starter I typically see 3-3.5 times increase in size at peak. The levain will smell sweet with only a mild tang.
In a sauce pan set on medium heat, stir the milk and flour until blended. Then cook for several minutes until well thickened, stirring regularly with a spoon or heat-resistant spatula. Let cool in the pan or, for faster results, in a new bowl. Theoretically it should reach 65ºC (149ºF) but I don’t find I need to measure the temperature as the tangzhong gelatinizes at this temperature. You can prepare this the night before and refrigerate it, ensure that it is covered to prevent it from drying out.
In the bowl of a stand mixer, add the milk (consider holding back 10 g of milk and adding later if this is the first time you’re making this), egg, tangzhong, salt, sugar and levain. Mix and then break up the levain into many smaller pieces. Next add the flour, I like to use my spatula to mix until there aren’t many dry areas. Allow the flour to hydrate (fermentolyse) for 15 minutes. Mix on low speed and then medium speed until moderate gluten development this may take 5-10 mins. You may want to scrape the sides of the bowl during the first 5 minutes of mixing. Next drizzle in the melted butter a little at a time, or alternatively add room temperature butter one pat at a time. Slow the mixer down to avoid splashing the butter at you. The dough may come apart, be patient, continue to mix until it comes together before drizzling or adding in more butter. Once all the butter has been added and incorporated increase the speed gradually to medium. Add the mashed sweet potatoes gradually. Mix at medium speed until the gluten is well developed, approximately 10 mins. You will want to check gluten development by windowpane during this time and stop mixing when you get a good windowpane. You should be able to pull a good windowpane.
You can definitely mix and knead these by hand as I did. I melted the butter and added it with the wet ingredient. Then follow the instructions instead kneading by slap and folding.
On the counter, shape the dough into a tight ball, cover in the bowl and ferment for 2.5-3.5 hours at 82ºF. There should be some rise visible at this stage.
You can next place the dough into the fridge to chill the dough for about 1.5 hours, this makes rolling the dough easier to shape. Remember, if you do so the final proof will take longer. Alternatively, you can do a cold retard in the fridge overnight, however, you may find that this increases the tang in your bread.
Line a large cookie tray with parchment paper. Punch the dough down and then divide into 8 equal portions. Form each into tight boules. Place on a parchment lined cookie tray. Cover them and allow them to fully proof about 4-6 hours, they should pass the poke test.
After about 30 mins of proofing time, whisk your remaining egg and milk and then brush the small boules.
About 30 mins prior to end of final proof preheat the oven to 350°F.
Immediately prior to baking brush the dough again with the egg and milk mixture.
Bake the buns uncovered for 30-35 minutes or until the internal temperature is at least 190F. Cover if your rolls get brown early in the baking process.
These look perfect for burgers and anything else you can fit in between them. I love using sweet potatoes and the combo with a Tangzhong is ideal.
Thank you Ian, your use of sweet potatoes was what gave me the inspiration to add sweet potatoes to my bread a few years back.